Clandestine
by Sable Supernova
Summary: Sirius Black only ever loved one woman, but circumstances were never in their favour. One shot.


Written for the following prompts:

All About You Challenge: Write Cross Gen

Unusual Ships Challenge: Sirius/Minerva

Weekly Elimination Weird Prompt Thing: Sirius/Minerva - must be requited / "Don't sneak up on me like that! I'm going to have to put a bell on you or something." / "I've been lonely." / takes place during PoA / mouse shaped squeaky toy (1 pt) / a ribbon with a bell on it (3 pts) / Sirius wears a dog collar while in human form (2 pts) / "Does the age difference really bother you that much?" (3 pts) / crystal hairpin (5 pts) / lamp (1 pt) / a blanket that smells of wet dog (2 pts) / Buckbeak (4 pts) / "I think he likes you." (2 pts) / "Is your middle name really Orion?" / "Yeah, why?" / "Well, I suppose it's fitting since that makes your initials S O B..." (4 pts) [obviously the second speaker must be Sirius, but the other person can be anyone]

Word count: 3,730

Warnings for: Mature language, slight sexual situations, and teacher/student relationship. He is of age, at seventeen, but still, I know some people don't like it.

Thank you to the lovely RainbowJH for being my beta for this story :)

* * *

 **Clandestine**

Sirius and his friends were chatting and laughing while they waited for McGonagall to arrive. When the usual tabby cat walked in, it transfigured into their teacher making her way to her desk. Sirius held back a smile and sat up straighter in his chair. As she sat down, a loud, high squeak echoed around the classroom. Sirius wasn't able to contain his laughter as the Transfiguration Professor stood and picked up a toy mouse, brown and furry, from her chair.

"Detention, Black," she said, with barely a glance at the boy.

"Oh, Professor! If you wanted to get me alone, you just had to ask!" he announced, much to the hilarity of his friends. Minerva McGonagall did not find it funny.

"That's quite enough, Black, unless you want house points deducted as well," she warned.

"I think he likes you," came the unhelpful stage-whisper of James Potter, grinning from ear to ear as Sirius attempted to whack him around the head.

"Five points from Gryffindor," she announced, turning to the board to enchant the chalk to begin the lesson. If Sirius wasn't mistaken, he saw a slight blush creep onto her cheeks as she turned to face away from the class.

* * *

Sirius glanced at his pocket-watch, and was more than surprised to see that he was early. He wasn't sure he had ever been early for a detention in his life. He took a deep sigh and knocked on the door, ready to face his punishment. Professor McGonagall opened the door as soon as he finished knocking, as if she'd been waiting for him.

"Come in, Black," she demanded.

Sirius was feeling much more humble without an audience, and complied without even the hint of his usual grin.

McGonagall swept her wand around the room and all the tables and chairs moved to the edges of the room and then into neat stacks. Summoning a bucket of soapy water and a washcloth, she turned to Sirius with an air of authority.

"The floors need cleaning. You'll leave when it's complete. No magic," she announced, holding her hand out for his wand, knowing he knew the routine by now. He handed it over and made his way towards the bucket that stood in the middle of the room.

Minerva McGonagall had learned by now that it was better not to leave him alone - he often found his way around the rules. Instead, she made her way over to her desk, placing his wand down in front of her, and began to mark her fifth years' homework.

After a few moments of silence, Sirius began, "So, how's your day been?"

McGonagall held back a smile. It was a routine they'd fallen into, where he would ask questions and try to engage in conversation, and she rarely took the bait.

"Long, now carry on as you were," she replied curtly.

"I'm only trying to make the best of the situation, Professor," he replied.

"There isn't supposed to be a 'best' in this situation, Sirius, it's a punishment," she informed him. She found herself confused, however, when she looked up to see him smiling. "Is there something you find amusing, Mr Black?"

"You called me Sirius," he said, before turning back to his work. McGonagall merely sighed and carried on with her own task.

The silence once again did not last long.

"What made your day long, then?" he asked.

"Students like you," she replied, as quick with her wit as she had been as a young witch.

"Oh, nice comeback," he told her with a grin. "I'm impressed."

"Sirius, is your middle name really Orion?" she asked him with a small smile.

"Yeah, why?" he replied, curious.

"Well, I suppose that's fitting since that makes your initials S O B..." she replied, trailing off at the end of the sentence as if in thought.

"Why's that?" he asked.

"Because you're a real son of a-" she cut off her own sentence before finishing. While Sirius Black may have been seventeen now, of age and a seventh year, she would not besmirch her honourable reputation and career for anyone - least of all Sirius Black.

He'd cottoned on to what she wanted to say, though, and stood with his characteristic smirk, his work forgotten, as he made his way over to her desk.

"I'm not sure that's the kind of language you should be using around a student, Professor," he chastised.

"You aren't exactly an average student, Mr Black," she told him, her face set hard.

"Am I not?" His eyebrow raised questioningly, taunting his Professor.

She looked for a moment as if she was about to answer him, before changing her mind and saying, "Get back to work, Mr Black."

* * *

It was less than a week later when Sirius Black found himself alone in detention with Minerva McGonagall again. He'd written on her blackboard before class so that the message greeting her when she walked into the classroom was, " _Sirius Black would like to inform Professor McGonagall that he will not be present in class this morning as he saw her on his way to breakfast and suddenly forgot to pay attention to where he was going and walked headfirst into a wall._ " And of course, he was not around to punish directly. After clearing the board, she sat down at her desk amidst the snickers of her class and wrote a note informing Sirius of his detention that evening before she began her lesson.

* * *

"James, punch me," Sirius said, imploring his best friend who eyed him with suspicion.

"Why?" James queried, running a hand through his already messy hair.

"Because I've got detention with McGonagall in an hour and I need to look like I walked into a wall this morning," he explained.

"Oh, yeah," James grinned, "But I'm still not punching you."

Sirius sighed in frustration. "Remus? Peter?" Both of them shook their heads. "I can't believe I'm about to do this," Sirius said before setting off at a brisk pace towards their dormitory door. He closed his eyes against the impact, but didn't flinch.

"Oh, fuck!" he announced before the blood came pouring out of his now broken nose.

* * *

When Sirius stood outside of McGonagall's classroom that evening, he was quite surprised by the mess he'd made of his once-beautiful face. Looking at himself in his two-way mirror that was currently just a mirror, he saw his eyes were blackening quite profusely, his forehead was a shade of blue and his nose was a lovely bright red and wonky.

Smiling, he knocked on the door.

"Black," McGonagall announced as she opened the door, before looking up at him. "Oh, my."

Sirius walked past her to enter the room, not reacting to her shock.

"Take a seat, Mr Black. Since you missed the lesson, you can sit it now," she told him.

"So, I'm still being punished even though I really am injured?" he asked as he took a seat.

"Absences due to sickness or injury must be authorised by the Matron. Did you even visit the Hospital Wing?" she asked as she took her own seat opposite him, at her own desk. She had no papers to grade that evening, so she sat with nothing on her desk but her usual lamp and a book.

"No," he replied. "But, if I miss lessons, I get private tutoring?" he asked, a hopeful note in his voice.

"Consider this an exception. If you intend to miss more lessons, you will not be receiving help from me."

"Don't you value our alone time?" he asked, a mocking grin on his face.

"I have better things to do," she commented. Sirius couldn't help but notice her avoidance.

"Do you not get lonely?" he asked, pushing all the buttons, as if on some sort of high.

"That is not a concern of yours," McGonagall replied.

"It's only not a concern of mine if you don't want it to be," Sirius replied.

McGonagall looked up at the young man, unsure what he was meaning, unsure what was hidden in his words. It had been a long time before anyone, other than her colleagues, had truly cared for Minerva McGonagall. Sirius met her gaze as an equal, even as she said nothing.

In silence, Sirius stood and made his way around to where Minerva was seated, and she stood to meet him. She was taken aback by his bold actions, but she stood her ground. As he approached her, she leant back instinctively as he invaded her personal space, but she did not back away. He took her hand in his, and leant in slowly to place a soft kiss on her lips. He gave her time and opportunity to stop him, to back away, but she didn't.

"Sirius, this is highly inappropriate," she told him, but her lips remained parted, inviting, as she leaned towards him just a little.

When he kissed her again, she kissed him back. It happened all of a sudden; the desire caught hold of them and before they knew it, their breathing was heavy as they covered each other's lips in stolen kisses. As Minerva locked the door with a complex charm, Sirius put out the candles and torches in the room so that the only source of light left was coming from her lamp on the desk. Knocking her book from the mahogany surface, he lifted her onto her desk and crashed his body into hers, passion and desire his only masters.

* * *

For the remainder of his time at Hogwarts, the relationship was a secret. It took place only at night, after curfew, when the world was theirs and theirs alone. Sirius was thankful Filch had taken the Marauder's Map from him and his friends so that he didn't have to hide it in the evenings. His friends believed him when he said he was with other people. During the day, they were the perfect teacher and student, but when the night-time struck, they were completely enthralled by each other.

Minerva worried about their relationship after he left Hogwarts, thinking it wouldn't last, but she needn't have. They rented a room at the Hog's Head every Saturday night and arrived separately - Minerva often in disguise - so that if they had nothing else, they had that one night to be alone. The relationship was still kept undercover, and each had their own reasons for that, but those reasons seemed to be fading into the grey areas beneath certainty next to the strength of their affection for each other.

Minerva lay in his arms early one morning, her skin pressed up against his, and Sirius felt lucky. He always did when she was naked, knowing how she liked to cover up during the day. It was like the soft beauty under her corsets and gowns was his and his alone to enjoy.

"I ought to get back to school before my absence is noted," she said, sleep still clinging to her voice as her eyes began to open.

"Why is it so important?" he asked, trying to be casual about it.

"Because I'd rather not have to explain myself," she said, wrapping the quilt around her to protect her modesty as she sat up.

Sirius sat up, too, not caring about his own modesty as he pulled on a pair of jeans.

"And would that be such a bad thing?" he questioned.

"What on earth would I say in my defence?" she retorted, turning the question around on him.

"That you were enjoying an evening with your boyfriend?" he suggested.

She looked away, blushing in her anxiety.

"I couldn't," she said softly.

"Why not? Does the age difference really bother you that much?"

"Sirius, you were my student only a few months ago. While you and I can overlook that fact, there are many others that wouldn't. I can't jeopardize my career and reputation," she told him, though the pain in her eyes told Sirius it was hard for her to admit.

"Do you promise we will, one day? I just need you to promise that. I want to be able to introduce you to my friends as the woman I love," he told her, walking around the bed to kneel at her feet.

She kissed his forehead, a nurturing gesture. "One day. I promise."

* * *

Minerva McGonagall was teaching, but even she had to admit she'd been distracted all day. Looking fondly at her mahogany desk, and the same old red velvet lamp, she thought of how it was exactly a year ago that day that she and Sirius… She blushed just thinking about it and smiled. Classes were long over, but she found herself unable to focus on the homework in front of her – essays on the finer points of the Evanesco Charm.

There was a tap at the window, soft enough that it didn't startle her. She looked up to see the silhouette of a familiar owl staring at her and smiled as she waved her wand to open the window. Landing on her desk gracefully, the owl placed a neatly wrapped parcel on her desk. She offered the owl some treats before spotting the note on top of the parcel.

Opening it, the familiar scrawl brought a warmth to her heart even before she read the words:

 _Dearest Minnie,_

 _I know you aren't much taken to ornamentation, but I believe today is our anniversary, and to celebrate that, I wanted to give you something as beautiful as you are,_

 _Sincerely yours,_

 _Sirius_

With delicate fingers, she opened the parcel to reveal a small crystal hairpin. It was tasteful and ornate rather than ostentatious, and Minerva placed it on the palm of her hand with a fond smile. No, she was not moved by ornamentation, but she was moved by Sirius Black.

* * *

Many years later, Minerva sat alone in her chambers on that very same night. In her hands she held a blanket that smelled faintly of wet dog, and in her hair was a crystal hairpin. Tears rolled softly down her cheeks as she considered what had become of them.

All the facts seemed to speak for themselves; Sirius did not seem to be the man she thought he was. And yet, as she sat alone that evening, she knew a part of her did not believe it. A part of her missed him every day and regretted that she had never introduced him to anyone as hers. She hoped that a new piece of evidence would come to light that would prove him innocent; that he would one day receive his fair trial. What she would give to look into those bright eyes once more.

As she held the quilt up to her face, she knew those hopes would never see fruition. Above all, she knew she would never love again.

* * *

As Sirius stood alone outside the cave, above the village of Hogsmeade, he allowed his thoughts to return to Minerva. This close to where their love was known, it was hard for him to not think about her. He wondered which side of the story she believed, which version of events made the most sense to her. Now he was free, they would be able to carry on where they ended if they wished, but he was faced with the distinct possibility of living out the rest of his life as a free man alone.

And that was the thought that hurt the most. Above the betrayal of his friend, above his time in Azkaban, it was the loss of his love that cut right to the bone. He couldn't forget the job he'd come here to do, the fierce betrayal of Peter Pettigrew, but he also couldn't deny his desire to see his Minerva again.

He looked up at the full moon, shining high and bright above the treetops, and found his thoughts straying to his old friend, Remus. He wondered what kind of man he'd grown into. He'd heard he was back at Hogwarts too, and wondered how teaching was suiting him. Sirius liked to think it was suiting him very well. Remus had always been the nurturing type, even as student himself.

Sirius felt something on his elbow - a hand - and immediately jumped back and spun round to defend himself against his attacker, his heart pounding in his chest. He brought his arms up to fight back, tense and wild, and then his stormy grey eyes met green. He relaxed on instinct, standing, staring, as anxiety took over. He didn't know what she would say, but he waited.

"Sirius," she said, as much to herself as to him, her eyes wide in shock. "I thought I might find you here." Her voice was soft and quiet, but otherwise emotionless.

When she launched forward into his embrace, Sirius did not protest. He held her tightly, as if trying to make up for the years of missed occasions in one gesture. He felt tears in his eyes and did not fight them.

"I'm sorry," she said, as her own tears began to fall.

"What for?" he choked out.

"For thinking… for thinking I didn't know you. I was wrong. All those years… I was wrong," she told him, and while Sirius' heart jolted at the knowledge she'd believed him guilty, he was overwhelmed by her presence once more.

"What makes you so sure?" he questioned.

She pulled back a little so she could look at him, at her man. "The look in your eye," she said.

He pulled her in towards him and kissed her, letting her know that it was okay, now.

"I've been lonely," she admitted, before adding as an afterthought, "Without you."

"So have I," Sirius countered with a bitter laugh.

"I can't even imagine the horrors…" she began.

"Don't try. It's over now." his conviction was firm, and as if to make it concrete, he leaned down to kiss her again, quelling her words before they began.

* * *

Sirius was sitting outside of his cave, shivering in the old cloak she'd brought for him. He wasn't sure how he would have survived without her help, and he knew he would be eternally in her debt. He found, however, that he didn't mind it all that much. If there was anyone he'd want to owe a life debt to, it was her. Minerva McGonagall.

He felt something suddenly wrap around his neck loosely, and immediately began fighting it, looking around for his assailant, his pulse racing in his panic. He heard laughter and turned to find its source, the fight leaving him when he caught sight of her, laughing at him with love.

"Don't sneak up on me like that! I'm going to have to put a bell on you or something," he told her, and she laughed again as she moved to sit beside him, placing her hand on his knee as she leaned into his side.

Wrapping an arm around her, he used his other hand to feel the strange object around his neck.

"Is this a collar?" he asked, not knowing whether to be amused or annoyed.

She looked up at him with a mischievous grin and nodded. "More specifically, a dog collar."

"You're really funny, you know?" he replied, dry irony thick in his tone. "You're definitely getting a bell."

As he looked at her, the cold he'd felt just moments ago seemed to fade away into nothingness. He found himself wanting to say something, to tell her things he didn't know how to put into words. His life was miserable, most of the time, but she made it happier. He lived in the dark, and she brought the light. He lived for her visits, merely surviving in the emptiness between them. She looked at him as he looked at her. While his lips moved with words that never left his throat because they didn't sound like enough in his own head, she smiled.

"I love you, too," she told him, leaning in for a chaste kiss.

Sirius found himself overwhelmed by his love as he kissed her back, passion seeping into his actions. They kissed like they'd never kissed before, like each of them was a lifeline for the other, the only thing left that gave them the strength to go on. As the atmosphere heated, Sirius leaned back with a grin.

"I could always keep it on," he suggested.

* * *

The next morning, Minerva awoke to a tapping at her window. An owl was sitting patiently on the wall outside, and she opened her window to let him in. He placed a hastily wrapped box on her bedside table before flying away. There was no note, no card; Minerva unwrapped it with apprehension.

Opening the lid, she found herself staring down at a green ribbon, loosely tied, on which hung a small brass bell. She knew who it was from and smiled. That small trinket made her realise how she always had known Sirius, since the start. He always was a joker, even when times were hard, and he always followed through on his promises.

* * *

During the summer that followed, Sirius was surprised to find her still by his side. It would damage her reputation too much if the relationship was to come out - Sirius was adamant he wouldn't take that risk - and so they stuck to the shadows they'd come to know so well.

He was alone in Grimmauld Place, about to visit Buckbeak to feed him, when Minerva appeared in his fireplace. She fell straight into his arms without speaking a word, merely covering his face and neck with kisses, asking him a silent question.

"I have to feed Buckbeak," he told her, and she stepped back a little.

"I haven't yet met him, you know," she admitted.

He smiled and took her hand, beginning to lead her towards the stairs.

"He's basically family, so you should," he told her.

Up in the attic, Buckbeak eyed the food hungrily, and the woman warily.

"Buckbeak, as the only soul I know that I can say this to, I'd like you to meet my girlfriend, Minerva McGonagall," Sirius declared, smiling with pride as he glanced between the two of them. Minerva smiled back at him before bowing low towards the remarkable creature.

After a moment's consideration, Buckbeak accepted her, and bowed back.

* * *

So this is the first cross-gen I've ever written and I'd really appreciate it if you let me know what you thought!


End file.
